---
name: "approx"
section: "8"
platform: "linux"
package: "approx"
version: "5.13-1+b5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/approx"
---

# approx(8)

proxy server for Debian archive files

## NAME

approx - proxy server for Debian archive files

## SYNOPSIS

**approx** \[*OPTION*\]...

## DESCRIPTION

**approx** responds to HTTP requests made by [**apt-get**(8)](/apt-get/8.md). It maintains a cache of Debian archive files that have been previously downloaded, so that it can respond with a local copy when possible. If a file not in the cache is requested, **approx** will download it from a remote Debian repository and deliver the contents to the client, simultaneously caching it for future use.

## OPTIONS

- **-c** file, **--config** file

  Specify an additional configuration file. May be used multiple times.

## USAGE

**approx** is invoked by [**inetd**(8)](/inetd/8.md).

## EXAMPLES

Suppose that a client machine's */etc/apt/sources.list* file contains the following lines:

-

  deb     http://apt:9999/debian    testing main\
   deb     http://apt:9999/debian-security  testing-security main\
   deb-src http://apt:9999/debian    unstable main

In this example, *apt* is the hostname of the **approx** server machine on the local network. Each distribution, such as "debian" or "debian-security", is mapped to a remote repository in the **approx** server's configuration file.

For example, the *approx.conf* file on the **approx** server might contain the lines

-

  debian   http://ftp.debian.org/debian\
   debian-security http://security.debian.org/debian-security

The mapping scheme is very simple. If the *approx.conf* file contains the line

-

  repository	http://remote-host/initial/path

then any request to the **approx** server of the form

-

  http://approx-server/repository/rest/of/URL

is rewritten to

-

  http://remote-host/initial/path/rest/of/URL

when there is a "cache miss", and that file is cached as

-

  /var/cache/approx/repository/rest/of/URL

(Note that the repository name on the left-hand side is not included in the rewritten URL unless it is explicitly mentioned in the right-hand side's initial path.)

## FILES

- */etc/approx/approx.conf*

  Configuration file for **approx** and related programs.

- */var/cache/approx*

  Default cache directory for archive files.

## SEE ALSO

[*approx.conf*(5)](/approx.conf/5.md), [**inetd**(8)](/inetd/8.md), [**approx-import**(8)](/approx-import/8.md), [**apt-get**(8)](/apt-get/8.md), [*sources.list*(5)](/sources.list/5.md)

## AUTHOR

Eric Cooper \<ecc@cmu.edu\>